A novel sulfonated aromatic diamine monomer is used to provide thin-film composite (TFC) nanofiltration (NF) membranes with excellent performance and anti-fouling properties. A sulfonated TFC NF membrane was prepared through an interfacial polymerization reaction between amine agents in the aqueous phase and trimesoyl chloride (TMC) in the organic phase. Aqueous phase contained 2,5-diaminobenzene sulfonic add (2,5-DABSA) as a sulfonated amine and piperazine (PIP) as a routine amine. The membrane performance results indicated that at 50% 2,5-DABSA, water flux reached 61.2 L/m(2) . h demonstrating 34.2% higher water flux compared to membrane prepared by PIP without a significant change in salt rejection. The membrane was characterized using FT-IR, SEM, AFM, and contact angle methods. The results of contact angle and anti-fouling experiments proved that hydrophilicity of the membrane surface improved in the presence of 2,5-DABSA monomer. The high water flux was attributed to the presence of strong hydrophilic sulfonic groups at new polyamide layers leading to improved membrane anti-fouling properties. (C) 2015 Elsevier B.V. All rights reserved.